2. Patients who have autoimmune or rheumatologic disease. Patients with autoimmune diseases tend to have various autoantibodies in their serum. These naturally present autoantibodies in this patient group could cross-react with bevacizumab or ranibizumab. This would give the false impression that these patients have developed neutralizing antibodies against bevacizumab or ranibizumab, when in fact these naturally occurring cross-reactive autoantibodies were present in the patient all along and are not related to bevacizumab or ranibizumab exposure.